feat(fusion_clock): bi-weekly attendance filter — pay-period filters + picker

Reuse the existing Pay Period setting (Frequency + Anchor) as the single
source of truth via a shared pure helper (models/pay_period.py); fusion.clock.report
delegates to it. Add Current/Previous/Next Pay Period filters to the attendance
search view (search-method computed booleans on hr.attendance), a Bi-Weekly Period
picker wizard (pick start -> auto +2 weeks, editable; Apply opens the filtered list)
reachable from an Attendance menu item and a dashboard tile. Window follows the
configured frequency; TZ-correct via local-day boundaries. Bump 3.14.4 -> 3.15.0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

fusion_clock/tests/__init__.py

@@ -6,3 +6,4 @@ from . import test_shift_planner
 from . import test_photo_retention
 from . import test_schedule_driven
 from . import test_dashboard
+from . import test_pay_period